I would prefer no cameos but it would be very cool if we found items related to them, such as one of Deekin's books.
I also think this would be the only way to incorporate potential cameos. Even though earlier development studios like bioware/obsidian might have been granted a temporary use of the D&D IP and lore from wotc, the in-game stories and characters still belong to those companies. Ofc Larian can ask nicely if it's ok to put in a small cameo of example Neeshka but I don't think they will.